Unity Video Capture backend

.github/scripts/install-windows-unity-capture.ps1

@@ -0,0 +1,14 @@
+$ErrorActionPreference = 'Stop'
+
+. $PSScriptRoot\download-file.ps1
+
+$VERSION = "fe461e8f6e1cd1e6a0dfa9891147c8e393a20a2c"
+
+$FILENAME = "UnityCaptureFilter64bit.dll"
+$URL = "https://github.com/schellingb/UnityCapture/raw/$VERSION/Install/$FILENAME"
+
+$path = DownloadFile $URL $FILENAME
+
+$args = "/i:UnityCaptureDevices=2 /s $path"
+Write-Host "regsvr32" $args
+Start-Process -FilePath "regsvr32" -ArgumentList $args -Wait -Passthru -Verb "runAs"

.github/workflows/ci.yml

@@ -93,6 +93,7 @@ jobs:
       if: matrix.config.os-name == 'windows'
       run: |
         .github/scripts/install-windows-obs-virtual-cam.ps1
+        .github/scripts/install-windows-unity-capture.ps1
         .github/scripts/build-windows.ps1
       shell: pwsh
       env:

README.md

@@ -17,7 +17,9 @@ with pyvirtualcam.Camera(width=1280, height=720, fps=20) as cam:
         cam.sleep_until_next_frame()
 ```
 
-For more examples, including using different pixel formats like BGR, or selecting a specific camera device on Linux, check out the [`samples/`](samples) folder.
+pyvirtualcam uses the first available virtual camera it finds (see later section).
+
+For more examples, including using different pixel formats like BGR, or selecting a specific camera device, check out the [`samples/`](samples) folder.
 
 See also the [API Documentation](https://letmaik.github.io/pyvirtualcam).
 
@@ -39,7 +41,13 @@ pyvirtualcam relies on existing virtual cameras which have to be installed first
 
 To use the OBS virtual camera, simply [install OBS](https://obsproject.com/).
 
-Note that OBS provides a single camera instance only, so it is *not* possible to send frames from Python, capture the camera in OBS, mix it with other content, and output it again as virtual camera.
+Note that OBS provides a single camera instance only, so it is *not* possible to send frames from Python to the built-in OBS virtual camera, capture the camera in OBS, mix it with other content, and output it again to OBS' built-in virtual camera. To achieve such a workflow, use another virtual camera from Python (like Unity Capture) so that OBS' built-in virtual camera is free for use in OBS.
+
+### Windows: Unity Capture
+
+[Unity Capture](https://github.com/schellingb/UnityCapture) provides a virtual camera originally meant for streaming Unity games. Compared to most other virtual cameras it supports RGBA frames (frames with transparency) which in turn can be captured in [OBS](https://obsproject.com/) for further processing.
+
+To use the Unity Capture virtual camera, follow the [installation instructions](https://github.com/schellingb/UnityCapture#installation) on the project site.
 
 ### macOS: OBS
 
@@ -66,9 +74,6 @@ sudo modprobe v4l2loopback devices=1
 
 For further information, see the [v4l2loopback documentation](https://github.com/umlaeute/v4l2loopback).
 
-If the `device` keyword argument is not given, then pyvirtualcam uses the first available v4l2loopback virtual camera it finds.
-The camera device name can be accessed with `cam.device`.
-
 ## Build from source
 
 ### Linux/macOS

pyvirtualcam/camera.py

@@ -105,8 +105,9 @@ def register_backend(name: str, clazz):
     BACKENDS[name] = clazz
 
 if platform.system() == 'Windows':
-    from pyvirtualcam import _native_windows_obs
+    from pyvirtualcam import _native_windows_obs, _native_windows_unity_capture
     register_backend('obs', _native_windows_obs.Camera)
+    register_backend('unitycapture', _native_windows_unity_capture.Camera)
 elif platform.system() == 'Darwin':
     from pyvirtualcam import _native_macos_obs
     register_backend('obs', _native_macos_obs.Camera)
@@ -128,6 +129,9 @@ class PixelFormat(Enum):
     BGR = '24BG'
     """ Shape: ``(h,w,3)`` """
 
+    RGBA = 'ABGR'
+    """ Shape: ``(h,w,4)`` """
+
     GRAY = 'J400'
     """ Shape: ``(h,w)`` """
 
@@ -152,6 +156,7 @@ def __repr__(self):
 FrameShapes = {
     PixelFormat.RGB: lambda w, h: (h, w, 3),
     PixelFormat.BGR: lambda w, h: (h, w, 3),
+    PixelFormat.RGBA: lambda w, h: (h, w, 4),
     PixelFormat.GRAY: lambda w, h: (h, w),
     PixelFormat.I420: lambda w, h: w * h * 3 // 2,
     PixelFormat.NV12: lambda w, h: w * h * 3 // 2,
@@ -172,13 +177,15 @@ class Camera:
 
         - ``v4l2loopback`` (Linux): ``/dev/video<n>``
         - ``obs`` (macOS/Windows): ``OBS Virtual Camera``
+        - ``unitycapture`` (Windows): ``Unity Video Capture``, or the name you gave to the device
     :param backend: The virtual camera backend to use.
         If ``None``, all available backends are tried.
 
         Built-in backends:
 
         - ``v4l2loopback`` (Linux)
         - ``obs`` (macOS/Windows)
+        - ``unitycapture`` (Windows)
     :param print_fps: Print frame rate every second.
     :param kw: Extra keyword arguments forwarded to the backend.
         Should only be given if a backend is specified.

pyvirtualcam/native_macos_obs/virtual_output.h

@@ -70,8 +70,8 @@ class VirtualOutput {
             case libyuv::FOURCC_RAW:
             case libyuv::FOURCC_24BG:
             case libyuv::FOURCC_J400:
-                // RGB|BGR|GRAY -> ARGB -> UYVY
-                _buffer_tmp.resize(argb_frame_size(width, height));
+                // RGB|BGR|GRAY -> BGRA -> UYVY
+                _buffer_tmp.resize(bgra_frame_size(width, height));
                 _buffer_output.resize(out_frame_size);
                 break;
             case libyuv::FOURCC_I420:
@@ -136,18 +136,18 @@ class VirtualOutput {
         switch (_frame_fourcc) {
             case libyuv::FOURCC_RAW:            
                 out_frame = _buffer_output.data();
-                rgb_to_argb(frame, tmp, _frame_width, _frame_height);
-                argb_to_uyvy(tmp, out_frame, _frame_width, _frame_height);
+                rgb_to_bgra(frame, tmp, _frame_width, _frame_height);
+                bgra_to_uyvy(tmp, out_frame, _frame_width, _frame_height);
                 break;
             case libyuv::FOURCC_24BG:
                 out_frame = _buffer_output.data();
-                bgr_to_argb(frame, tmp, _frame_width, _frame_height);
-                argb_to_uyvy(tmp, out_frame, _frame_width, _frame_height);
+                bgr_to_bgra(frame, tmp, _frame_width, _frame_height);
+                bgra_to_uyvy(tmp, out_frame, _frame_width, _frame_height);
                 break;
             case libyuv::FOURCC_J400:
                 out_frame = _buffer_output.data();
-                gray_to_argb(frame, tmp, _frame_width, _frame_height);
-                argb_to_uyvy(tmp, out_frame, _frame_width, _frame_height);
+                gray_to_bgra(frame, tmp, _frame_width, _frame_height);
+                bgra_to_uyvy(tmp, out_frame, _frame_width, _frame_height);
                 break;
             case libyuv::FOURCC_I420:
                 out_frame = _buffer_output.data();